The present invention relates to a pneumatic tire, more particularly relates to a pneumatic tire using a rubber containing a specific hydrogenated NBR (that is, xe2x80x9ca rubber composition containing, based on a total 100 parts by weight of rubber containing at least 40 parts by weight of an ethylenic unsaturated nitrile-conjugated diene-based highly saturated rubber having a content of conjugated diene units of not more than 30 percent, 0 to 120 parts by weight of zinc methacrylate and 0 to 60 parts by weight of carbon black and having a total amount of formulations of zinc methacrylate and carbon black of 10 to 120 parts by weightxe2x80x9d) for part or all of the tire.
Known in the art is the use of hydrogenated NBR for tires etc., making use of the fact that vulcanized formulations of this with a zinc compound, methacrylic acid, and organic peroxide have extremely high strength characteristics (Japanese Unexamined Patent Publication (Kokai) No. 1-306443). There is the problem, however, that such hydrogenated NBR compositions are generally extremely difficult to bond with general purpose rubbers. Techniques are also being developed for bonding general purpose rubbers for tires and such members through a specific bonding layer to solve the problem of bonding (Japanese Unexamined Patent Publication (Kokai) No. 5-185805). Even with this method, however, the bonding force with the adjoining rubber is not sufficient. When applied to a tire, not only does the durability fall, but also, since two bonding layers are needed, there is the problem that the productivity of the tire worsens.
Therefore, an object of the present invention is to provide a pneumatic tire reducing the weight of the tire, lightening the rolling resistance, and improving the durability, abrasion resistance, cut resistance, and driving stability by constituting part or all of the part members in a tire by a rubber containing a specific hydrogenated NBR or by using a specific bonding rubber layer for the bonding layer between such part members and parts comprised of other general purpose rubbers when using the rubber containing a specific hydrogenated NBR for part of the part members and not requiring the inner layer required in the past due to the superior air barrier property of the hydrogenated NBR. Another object of the present invention is to provide a pneumatic tire using such a rubber containing a hydrogenated NBR as a reinforcing layer for part of the inside and outside layers of the tire or using it as a white or colored decorative member for the outer surface of the tire.
According to a first aspect of the present invention, an object of the present invention is the provision of a pneumatic tire which can strikingly improve the abrasion resistance and rolling resistance or improve the driving stability feeling and lighten the weight without reducing the high speed durability by applying a specific hydrogenated NBR rubber composition including the rubber containing a hydrogenated NBR and zinc methacrylate and/or carbon black for the members of the cap tread and/or under tread of the tire and further by using a specific bonding layer to strongly bond the cap tread and adjoining under tread or belt layer or the under tread and the adjoining rubber layer.
According to the present invention, there is provided a pneumatic tire having a cap tread which is comprised of a rubber composition containing, based on a total 100 parts by weight of rubber containing at least 70 parts by weight of hydrogenated NBR, 0 to 80 parts by weight of zinc methacrylate and 0 to 40 parts by weight of carbon black and having a total of the formulations of zinc methacrylate and carbon black of 10 to 120 parts weight, and providing between the cap tread and the adjoining rubber layer (normally an under tread layer or belt layer) a bonding rubber layer comprised of a rubber composition containing, based on a total 100 parts by weight of (A) at least one type of diene-based rubber selected from the group consisting of a natural rubber, polyisoprene rubber, polybutadiene rubber, and conjugated diene-aromatic vinyl copolymer rubber and (B) an acrylonitrile-butadiene copolymer rubber, (C) 5 to 80 parts by weight of an aromatic petroleum resin having an average molecular weight of 300 to 1500, a softening point of 50 to 160xc2x0 C., and an iodine adsorption value of at least 20 g/100 g.
Further, according to the present invention, there is provided a pneumatic tire inserting between a cap tread and belt layer an under tread comprised of a rubber composition containing, based on a total 100 parts by weight of rubber containing at least 40 parts by weight of a hydrogenated NBR, 0 to 120 parts by weight of zinc methacrylate and 0 to 40 parts by weight of carbon black and having a total of the formulations of zinc methacrylate and carbon black of 10 to 120 parts by weight, and providing between the under tread and adjoining rubber layer a bonding rubber layer comprised of a rubber composition containing, based on a total 100 parts by weight of (A) at least one type of diene-based rubber selected from the group consisting of a natural rubber, polyisoprene rubber, polybutadiene rubber, and conjugated diene-aromatic vinyl copolymer rubber and (B) an acrylonitrile-butadiene copolymer rubber, (C) 5 to 80 parts by weight of an aromatic petroleum resin having an average molecular weight of 300 to 1500, a softening point of 50 to 160xc2x0 C., and an iodine adsorption value of at least 20 g/100 g.
Further, according to the present invention, there is provided a pneumatic tire having, at a layer under a cap tread of a hydrogenated NBR rubber composition comprised of the composition of said cap tread, an under tread of a hydrogenated NBR rubber composition comprised of the composition of the under tread and having, between the under tread and the adjoining rubber layer, a bonding layer of a rubber composition comprised of the composition of the bonding rubber.
Further, according to the present invention, there is provided a pneumatic tire characterized in that a thickness of the bonding rubber layer positioned between the cap tread and the adjoining rubber layer is 0.1 to 4 mm; the thickness of the bonding layer positioned between the under tread and the adjoining rubber layer is 0.1 to 0.5 mm; the ratio of weight (A)/(B) of the component (A) and component (B) in the bonding rubber layer is 90/10 to 10/90; and the bonding rubber layer further contains at least one co-cross-linking agent selected from the group consisting of a methacrylic acid higher ester, triallyl isocyanurate, metal salt of methacrylic acid or acrylic acid, diallyl phthalate ester, and 1,2-polybutadiene and is cross-linked by an organic peroxide.
Further, according to a second aspect of the present invention, an object of the present invention is to provide a pneumatic tire which improves the run flat property by constituting a crescent sectional-shaped reinforcing liner inserted between a carcass layer of a side wall portion and inner liner layer by a specific rubber material and which strongly bonds the reinforcing liner and the adjoining rubber layer through a specific bonding rubber layer comprised of one layer.
According to the present invention, there is provided a pneumatic tire having at a side wall portion a crescent sectional-shape reinforcing liner layer comprised of a rubber composition containing, based on a total 100 parts by weight of a rubber containing 70 to 100 parts by weight of an ethylenic unsaturated nitrile-conjugated diene-based highly saturated copolymer rubber having a content of conjugated diene units of at least 30 percent by weight, 20 to 120 parts by weight of zinc methacrylate, containing no carbon black or not more than 40 parts by weight of the same, and having a total of formulations of zinc methacrylate and carbon black of not more than 120 parts by weight and bonding with an adjoining rubber layer through a bonding rubber layer containing, based on a total 100 parts by weight of (A) at least one type of diene-based rubber selected from the group consisting of a natural rubber, polyisoprene rubber, polybutadiene rubber, and conjugated diene-aromatic vinyl copolymer rubber and (B) an acrylonitrile-butadiene copolymer rubber, (C) 5 to 80 parts by weight of an aromatic petroleum resin having an average molecular weight of 300 to 1500, a softening point of 50 to 160xc2x0 C., and an iodine adsorption value of at least 20 g/100 g.
Further, according to the present invention, there is provided a pneumatic tire characterized in that a thickness of the bonding rubber layer is 0.1 to 2.0 mm; the ratio of weight of the (A) diene-based rubber and (B) acrylonitrile-butadiene copolymer rubber contained in the bonding rubber layer is A:B=10:90 to 90:10; and the bonding rubber layer further contains at least one co-cross-linking agent selected from the group consisting of a methacrylic acid higher ester, triallyl isocyanurate, metal salt of methacrylic acid or acrylic acid, diallyl phthalate ester, and 1,2-polybutadiene and is cross-linked by an organic peroxide.
Further, according to a third aspect of the present invention, an object of the present invention is to provide a tire improved in durability and improved in the driving stability since it becomes possible to increase the rigidity of a side wall portion without reducing the durability of the reinforcing rubber member of the bead portion and without increasing the tire mass and it becomes possible to bond the members strongly to the adjoining rubber layers by using a hydrogenated NBR composition containing a specific hydrogenated NBR and zinc methacrylate for the reinforcing rubber member of the bead portion and using a bonding rubber composition comprised of a specific diene-based rubber, NBR, and aromatic petroleum resin for the bonding rubber layer.
According to the present invention, there is provided a tire providing a rubber composition containing, based on a total 100 parts by weight of a rubber containing 70 to 100 parts by weight of an ethylenic unsaturated nitrile-conjugated diene-based highly saturated copolymer rubber having a content of conjugated diene units of not more than 30 percent by weight, 40 to 120 parts by weight of zinc methacrylate, containing no carbon black or containing not more than 40 parts by weight of the same, and having a total of formulations of zinc methacrylate and carbon black of not more than 120 parts by weight as the reinforcing rubber layer of the bead portion at least at part of a bead filler and/or providing it as a reinforcing bead filler at the outside of the axial direction of the carcass turn up layer, and bonding with the adjoining rubber layer through a bonding rubber layer containing, based on a total 100 parts by weight of (A) at least one type of diene-based rubber selected from the group consisting of a natural rubber, polyisoprene rubber, polybutadiene rubber, and conjugated diene-aromatic vinyl copolymer rubber and (B) an acrylonitrile-butadiene copolymer rubber, (C) 5 to 80 part5 by weight of an aromatic petroleum resin having an average molecular weight of 300 to 1500, a softening point of 50 to 160xc2x0 C., and an iodine adsorption value of at least 20 g/100 g.
Further, according to the present invention, there is provided a tire characterized in that a thickness of the bonding rubber layer is 0.1 to 2.0 mm; the (A) diene-based rubber and (B) acrylonitrile-butadiene copolymer rubber contained in the bonding rubber layer have a ratio by weight in the range of A:B=10:90 to 90:10; and the bonding rubber layer further contains at least one co-cross-linking agent selected from the group consisting of a methacrylic acid higher ester, triallyl isocyanurate, metal salt of methacrylic acid or acrylic acid, diallyl phthalate ester, and 1,2-polybutadiene and is cross-linked by an organic peroxide.
Further, according to a fourth aspect of the present invention, an object of the present invention is, taking note of the characteristic of hydrogenated NBR of having a higher rigidity and lower tan xcex4 than general purpose rubber, being superior in heat resistance, weather resistance, and abrasion resistance, and having a low unvulcanized viscosity contrary to its hardness, to use a rubber composition containing a specific hydrogenated NBR and zinc methacrylate and/or carbon black for the carcass coat of a pneumatic tire, and thereby has as its object to provide a pneumatic tire comprised of a rubber which exhibits a high strength with a reduction in the amount of use of carbon or without formulation of the same, has an extremely low tan xcex4, and can reduce the rolling resistance of the tire by use of this for the carcass coat, can further improve the driving stability, and, since the hydrogenated MPR is also superior in air barrier property, enables elimination of the inner liner (air barrier layer) and a major reduction in weight when used for the carcass, and further uses a rubber bonding layer of a specific composition between the carcass coat and the adjoining rubber and thereby improves the bonding force and also increases the productivity.
According to the present invention, there is provided a pneumatic tire covering the reinforcing cord by a rubber composition containing, based on a total 100 parts by weight of a rubber containing at least 70 parts by weight of an ethylenic unsaturated nitrile-conjugated diene-based highly saturated rubber (hydrogenated NBR) having a content of conjugated diene units of not more than 30 percent by weight, 0 to 90 parts by weight of zinc methacrylate and 0 to 40 parts by weight of carbon black and having a total of formulations of zinc methacrylate and carbon black of 10 to 90 parts by weight and further using at least one carcass layer of 1.1 dxe2x89xa6Txe2x89xa63.6 d where the diameter of the reinforcing cord is d and the thickness of the reinforcing cord covering is T.
Further, according to the present invention, there is provided a pneumatic tire of the above composition which provides between the carcass and the tire members positioned at the outside of the carcass such as a belt and side wall, etc., a rubber composition layer containing, based on 100 parts by weight of (A) at least one type of diene-based rubber selected from the group consisting of a natural rubber, polyisoprene rubber, polybutadiene rubber, and conjugated diene-aromatic vinyl copolymer rubber and (B) an acrylonitrile-butadiene copolymer rubber, (C) 5 to 80 parts by weight of an aromatic petroleum resin having an average molecular weight of 300 to 1500, a softening point of 50 to 160xc2x0 C., and an iodine adsorption value of at least 20 g/100 g.
Further, according to the present invention, there is provided a pneumatic tire characterized in that a thickness of the rubber composition positioned at the outside of the carcass is 0.1 to 1.7 mm; the ratio of weight of (A) and (B) of the rubber composition is (A)/(B)=90/10 to 10/90; the rubber composition further contains at least one co-cross-linking agent selected from the group consisting of a methacrylic acid higher ester, triallyl isocyanurate, metal salt of methacrylic acid or acrylic acid, diallyl phthalate ester, and 1,2-polybutadiene and is cross-linked by an organic peroxide; and the carcass does not have an air barrier layer.
Further, according to a fifth aspect of the present invention, an object of the present invention is to provide a pneumatic tire which reinforces at least part of the side wall of the tire by a rubber containing a hydrogenated NBR or a rubber composition containing this and zinc methacrylate and/or carbon black, and further uses a specific adhesive to ensure bonding with the adjoining rubber layer and thereby reduce the thickness of the side wall and accordingly reduce the weight of the tire without lowering the durability and cut resistance.
Further, an object of the present invention is to provide a pneumatic tire which, by using a hydrogenated NBR rubber or a hydrogenated NBR rubber composition containing zinc methacrylate for the white or colored ribbon or letter parts positioned at the surface of the side wall part of the tire, is greatly improved in weather resistance and cut resistance and which does not necessarily require an exclusive mold or can reduce the thickness of the rubber at the ribbon or letter part, can lighten the weight of the tire since not requiring a protective layer for preventing migration of the polluting antioxidant, and uses a specific adhesive to ensure bonding wih the adjoining rubber layer and thereby also improves the durability of the tire.
According to the present invention, there is provided a pneumatic tire which reinforces at least part of the side wall by a reinforcing layer comprised of a rubber composition containing, based on a total 100 parts by weight of rubber containing at least 40 parts by weight of the hydrogenated NBR, 0 to 120 parts by weight of zinc methacrylate and 0 to 30 parts by weight of carbon black and having a total of formulations of zinc methacrylate and carbon black of 10 to 120 parts by weight.
Further, according to the present invention, there is provided a pneumatic tire providing a rubber composition colored other than black at the surface of the side wall portion wherein the rubber composition is comprised of a rubber composition containing, based on a total 100 parts by weight of a rubber containing at least 30 parts by weight of a hydrogenated NBR, 0 to 90 parts by weight of zinc methacrylate and the thickness is not less than 0.5 mm.
Further, according to the present invention, there is provided a pneumatic tire providing between the reinforcing layer or rubber composition providing layer and the rubber layers adjoining these a bonding rubber layer comprised of a rubber composition containing, based on a total 100 parts by weight of (A) at least one type of diene-based rubber selected from the group consisting of a natural rubber, polyisoprene rubber, polybutadiene rubber, and conjugated diene-aromatic vinyl copolymer rubber and (B) an acrylonitrile-butadiene copolymer rubber, (C) 5 to 80 parts by weight of an aromatic petroleum resin having an average molecular weight of 300 to 1500, a softening point of 50 to 160xc2x0 C., and an iodine adsorption value of at least 20 g/100 g.
Further, according to the present invention, there is provided a pneumatic tire characterized in that a thickness of the bonding rubber layer is 0.1 to 2.0 mm; the ratio of weight (A)/(B) of the (A) component and (B) component in the bonding rubber layer is 90/10 to 10/90; and the bonding rubber layer further contains at least one co-cross-linking agent selected from the group consisting of a methacrylic acid higher ester, triallyl isocyanurate, metal salt of methacrylic acid or acrylic acid, diallyl phthalate ester, and 1,2-polybutadiene and is cross-linked by an organic peroxide.
Further, according to a sixth aspect of the present invention, an object of the present invention, noticing the characteristics of hydrogenated NBR, is to provide a pneumatic tire which uses a rubber composition containing a specific composition of hydrogenated NBR and zinc methacrylate and/or carbon black for the air barrier layer of the pneumatic tire to achieve a high strength while reducing the amount of carbon used or without formulating it, which is extremely low in tan xcex4 and superior in air barrier property and therefore enables a reduction of weight through a lower thickness of the air barrier layer and further improves the driving stability, and which uses a specific composition of a rubber bonding layer between the air barrier layer and the adjoining rubber to improve the bonding force and increase the productivity.
According to the present invention, there is provided a pneumatic tire forming an air barrier layer by a rubber composition containing, based on a total 100 parts by weight of a rubber containing at least 70 parts by weight of an ethylenic unsaturated nitrile-conjugated diene-based highly saturated rubber having a content of conjugated diene units of not more than 30 percent by weight, 0 to 90 parts by weight of zinc methacrylate and 0 to 40 parts by weight of carbon black and having a total of formulations of zinc methacrylate and carbon black of 10 to 90 parts by weight and providing between the air barrier layer and the adjoining rubber a bonding rubber layer comprised of a rubber composition containing, based on a total 100 parts by weight of (A) at least one type of diene-based rubber selected from the group consisting of a natural rubber, polyisoprene rubber, polybutadiene rubber, and conjugated diene-aromatic vinyl copolymer rubber and (B) an acrylonitrile-butadiene copolymer rubber, (C) 5 to 80 parts by weight of an aromatic petroleum resin having an average molecular weight of 300 to 1500, a softening point of 50 to 160xc2x0 C., and an iodine adsorption value of at least 20 g/100 g.
Further, according to the present invention, there is provided a pneumatic tire characterized in that the thickness of the air barrier layer is 0.2 to 1.2 mm; the thickness of the bonding rubber layer is 0.1 to 1.1 mm; the ratio of weight of (A) and (B) of the rubber composition forming the bonding rubber layer is (A)/(B)=90/10 to 10/90, and the rubber composition forming the bonding rubber layer further contains at least one co-cross-linking agent selected from the group consisting of a methacrylic acid higher ester, triallyl isocyanurate, metal salt of methacrylic acid or acrylic acid, diallyl phthalate ester, and 1,2-polybutadiene and is cross-linked by an organic peroxide.
Further, according to a seventh aspect of the present invention, an object of the present invention is to provide a pneumatic tire improving the rim detachment and improving the driving stability without reducing the strength of the bead toe portion by providing at the bead toe portion a specific hydrogenated NBR composition having a hardness higher than rubber, a high strength with respect to deformation, and a small temperature dependency of the hardness compared with rubber.
According to the present invention, there is provided a pneumatic tire providing at least at part of the bead toe portion a rubber composition containing 70 to 100 parts by weight of an ethylenic unsaturated nitrile-conjugated diene-based highly saturated rubber having a content of conjugated diene units of not more than 30 percent by weight and containing 20 to 120 parts by weight of zinc methacrylate.
Further, according to the present invention, there is provided a pneumatic tire having a rubber composition of the bead toe portion further containing not more than 40 parts by weight of carbon black and having a total of formulations of zinc methacrylate and carbon black of not more than 120 parts by weight.
Further, according to the present invention, there is provided a pneumatic tire bonding the rubber member of the bead toe portion with the adjoining rubber layer through a bonding rubber layer comprised of a rubber composition containing, based on a total 100 parts by weight of (A) at least one type of diene-based rubber selected from the group consisting of a natural rubber, polyisoprene rubber, polybutadiene rubber, and conjugated diene-aromatic vinyl copolymer rubber and (B) an acrylonitrile-butadiene copolymer rubber, (C) 5 to 80 parts by weight of an aromatic petroleum resin having an average molecular weight of 300 to 1500, a softening point of 50 to 160xc2x0 C., and an iodine adsorption value of at least 20 g/100 g.
Further, according to the present invention, there is provided a pneumatic fire characterized in that the ratio of weight (A)/(B) of the component (A) and component (B) in the bonding rubber layer is 90/10 to 10/90; the thickness of the bonding rubber layer is 0.1 to 1.5 mm; and the bonding rubber layer further contains at least one co-cross-linking agent selected from the group consisting of a methacrylic acid higher ester, triallyl isocyanurate, metal salt of methacrylic acid or acrylic acid, diallyl phthalate ester, and 1,2-polybutadiene and is cross-linked by an organic peroxide.
Further, according to an eighth aspect of the present invention, there is provided a pneumatic tire having at least one carcass layer comprised of rubberized organic fiber cord or steel cord and at least two belt layers comprised of rubberized organic fiber cord or steel cord, wherein at least the carcass coat rubber and the belt coat rubber are comprised of a rubber composition containing, based on a total 100 parts by weight of a rubber containing at least 40 parts by weight of an ethylenic unsaturated nitrile-conjugated diene-based highly saturated rubber having a content of conjugated diene units of not more than 30 percent by weight, 0 to 120 parts by weight of zinc methacrylate and 0 to 60 parts by weight of carbon black and having a total of formulations of zinc methacrylate and carbon black of 10 to 120 parts by weight, and providing between the rubber composition and adjoining diene-based rubber a bonding rubber layer comprised of a rubber composition containing, based on a total 100 parts by weight of (A) at least one type of diene-based rubber selected from the group consisting of a natural rubber, polyisoprene rubber, polybutadiene rubber, and conjugated diene-aromatic vinyl copolymer rubber and (B) an acrylonitrile-butadiene copolymer rubber, (C) 5 to 80 parts by weight of an aromatic petroleum resin having an average molecular weight of 300 to 1500, a softening point of 50 to 160xc2x0 C., and an iodine adsorption value of at least 20 g/100 g.
Further, according to a ninth aspect of the present invention, there is provided a pneumatic tire which constitutes the carcass coat rubber, belt coat rubber, and bead filler rubber; the carcass coat rubber, belt coat rubber, bead filler, and side wall rubber; or carcass coat rubber, belt coat rubber and bead filler, side wall, rim cushion, and chafer rubber by the rubber containing the hydrogenated NBR, and provides the bonding rubber layer between the parts of these groups and the adjoining diene-based rubber members.
Further, according to a 10th aspect of the present invention, there is provided a pneumatic tire which uses at least one type of rubber selected from the group consisting of a diene-based rubber and butyl-based rubber for the cap tread and uses at least one type of rubber selected from the group consisting of a diene-based rubber, chloroprene-based rubber, butyl-based rubber, ethylene-propylene-based rubber, nitrile-based rubber, and hydrin-based rubber for the bead insulation or uses at least one type of rubber selected from the group consisting of a diene-based rubber and butyl-based rubber for the cap tread, and constitutes the rubber of the other portions by the rubber containing the hydrogenated NBR, and provides the bonding rubber layer between the same.
Further, according to the inventions of the eighth to 10th aspects, there is provided a pneumatic tire characterized in that the thickness of the bonding rubber layer is 0.1 to 2.0 mm; the ratio of weight (A)/(B) of (A) and (B) in the bonding rubber layer is 90/10 to 10/90; and the bonding rubber layer further contains at least one co-cross-linking agent selected from the group consisting of a methacrylic acid higher ester, triallyl isocyanurate, metal salt of methacrylic acid or acrylic acid, diallyl phthalate ester, and 1,2-polybutadiene and is cross-linked by an organic peroxide.
Further, according to an 11th aspect of the present invention, there is provided a pneumatic tire constituting the bead insulation rubber by at least one type of rubber selected from the group consisting of a diene-based rubber, chloroprene-based rubber, butyl-based rubber, ethylene-propylene-based rubber, nitrile-based rubber, and hydrin-based rubber, and does not provide the bonding rubber layer between the bead insulation and the adjoining rubber composition containing the hydrogenated NBR.
Further, according to a 12th aspect of the present invention, there is provided a pneumatic tire wherein the rubber at portions other than the bead insulation rubber is comprised of rubber containing the hydrogenated NBR or a pneumatic tire wherein the rubber at all portions constituting the tire is comprised of rubber containing the hydrogenated NBR.
Further, according to a 13th aspect of the present invention, there is provided a pneumatic tire using rubber containing the hydrogenated NBR colored a color other than black at least at part of the inside and outside surface of the tire.
Further, according to a 14th aspect of the present invention, there is provided a pneumatic tire not having an inner liner layer when using rubber containing a hydrogenated NBR for the rubber for predetermined part members.